Inhibitor



252. COMPOSITIONS, xrnirwrv Aug. 6, 1929. 1 Q DAvlDsON- 1,723,923

TNHIBITOR l Filed March 14, 1928 252. COMPOSITIONS,

Iiate-nte-d Aug. 6, 1929. wu UNITED STATES PATENT OFFICE.

JOSEPH Gr. DAVIDSON, 0F YONKERS, NEW YORK, ASSIGNOR TO CARBIDE & CARBONCHEMICALS CORP., A CORPORATION OF NEW YORK.

INHIBITOR.

Application filed March 14, 1,928. Serial No. 261,676.

a cold concentrated form. Such acid baths' tend to dissolve the steelbody as well as the scale coating, resulting in a waste of metal, andleaving the surface dirty and rough, instead of clean and smooth as isdesired. Many attempts have been made to reduce the rate of solution ofthe metal by the addition of such substances as arsenic, lead, barium,various cyanides, glue, flour, formaldehyde, quinoline, pyridine, etc..with varying success.

My invention utilizes the ethanolmies and thgkglzgglglues as inhibitorsin pickling baths, t ere y obtaining the new and useful result of asubstantial reduction in the rate of solution of the iron base withouteffect upon the speed and completeness of solution of the scale coating,as well as the avoidance of hydrogen embrittlement, of small objectssuch as wire, and a reduction of -acid fumes and vapor carried into theair by escaping hydrogen.

Other objects of my invention will be apparent from the followingdescription wherein,

Figures 1 and 2 are curves showing the rate of evolution by hydrogenfrom steel in a pickling bath treated with my new inhibitor incomparison with the various substances of the prior art, in variousconcentrations of acid. at various temperatures.

A commercially convenient ethanol-amine mixture, and portions thereofmay be replaced by the homologues such as the propanol amines, thebutanol amines, etc. all of these substances being substituted ammoniasof the aliphatic series. The piclrling bath when so treated shows anequally high rate of solution of the scale coating, and shows asubstantial reduction in rate of solution of the metal, as indicated bythe rate of evolution of hydrogen shown in the accompanying curves.

This composition of my invention is further highly advantageous becauseof the high boiling points of the ethanol amines, which cause them tostay in the pickling bath with a very small loss by evaporation.

The ethanol amines are more conveniently available on the commercialmarket at the present time and I find them suitable substances for usein the production of an embodiment of my invention. However, the othersubstances in the homologous series, such as propanol amines, etc.,above-mentioned, are equally useable, and it is desired that the use ofthe words hydroxy alkyl amines, in the appended claims shall beconstrued to include not only the ethanol amines as above-mentioned butthe higher homologues partaking of the same general nature.

The pickling bath of my invention is particularly usable with steel andiron products, but it is also useable in pickling baths for other metalssuch as copper etc.

It is likewise useable in other ways than as a pickling bath. I findthat a solution of acid as above-described with an addition of thehydroxy alkyl amines is conveniently useable for the cleaning out ofpipes and other metal conduits, in situ, the acid and amine solutionbeing passed through the pipes, to remove the lining of scale andobstructing matter which tends to form in piping systems with thepassage of time.

By the system of my invent-ion I have thus produced a new and usefultype of pickling bath having a much higher efciency, with 'a much lowerrate of solution of the free 10 Water solution and a dissolved ethanolamine homologue.

4. A pickling bath comprising a Water solution of an acid and aplurality of dissolved ethanol amines.

5. A pickling bath comprising Water solu 1,5

tion of sulphuric acid and an ethanol amine f dissolved therein.

6. A solution having a selective dissolving eect upon oxide compoundscomprising a Water solution of acid and a hydroxy alkyl 20 amine.

In testimony whereof, I a'ix my signature.

JOSEPH G. DAVIDSON.

